Bellkor breaks 9% improvement in the Netflix Challenge (as of 4/1)
netflixprize.com
netflixprize.com
(edited, brevity.)
That paper describes what they are doing.
http://en.wikipedia.org/wiki/Netflix_Prize
The class of algorithms that it's dealing with is called collaborative filtering and the Bell Labs team has done some impressive stuff there. The contest is more academic than it would seem on the surface, since as was mentioned in a recently posted article, the data set is rather narrow in scope. In other words, it's more of a collaborative filtering algorithms contest than a "find the best recommendation algorithm" contest.
Not to mention, the Netflix data has a scale of 1-5. Digg-like sites have scales from 0-1 (no vote, or vote), so that might further dilute the quality.
At a place like this, people are looking for "interesting tech articles", which is a really vague thing. Also, interesting articles tend to be things that you haven't seen before. So it is hard to build up a training set for that.